Acrylonitrile-butadiene-styrene (ABS) resins represented by acrylonitrile-butadiene-styrene terpolymers have excellent impact resistance, processability, mechanical strength, and heat resistance and also have an aesthetically pleasing appearance. Thus, ABS resins are used for various purposes in various fields, such as automobile parts, electrical and electronic products, and materials for buildings.
However, since ethylenically unsaturated polymers are present in a diene rubber used as an impact modifier in ABS resin, oxidation may easily occur in the resin due to ultraviolet light, light, and heat in the presence of oxygen, such that the appearance and color of the resin may be changed, and the mechanical properties of the resin may be deteriorated. Therefore, ABS resins are not suitable as exterior materials.
Therefore, when a thermoplastic resin having excellent physical properties, weather resistance, and aging resistance is prepared, ethylenically unsaturated polymers that are aged by ultraviolet light should not be present in the graft copolymer. Representative examples of resins meeting these requirements include acrylonitrile-styrene-acrylate (ASA) resins containing crosslinked alkyl acrylate rubber polymers. ASA resins have excellent weather resistance and aging resistance, and are used in various fields, such as automobiles, ships, leisure goods, building materials, and gardening goods.
In recent years, there has been growing interest in resins having excellent aesthetics, and accordingly, there is increasing demand for low-gloss resins. In particular, to satisfy consumers who prefer a luxurious appearance when purchasing interior materials for automobiles, exterior materials for electronic products, decorative sheets for furniture and buildings, and the like, it is necessary to develop products having low gloss and high adhesion properties.
To realize the above characteristics, post-processing, such as embossing the surface of a resin and coating the surface of a resin with a low-gloss material may be performed. However, when these methods are used, processing costs may be increased, and low gloss may be deteriorated due to wear during processing.
To realize a low gloss effect without a process such as the above-described matte coating, a method of scattering incident light by adjusting the smoothness of a resin to be larger than the wavelength range of visible light is mainly used. When preparing most low gloss resins, the following methods are used to lower gloss.
For example, a method of using a large-diameter conjugated diene rubber polymer having a particle diameter of μm or more, which is prepared by performing bulk polymerization, has been disclosed. Resins prepared by the method have good low gloss characteristics but have limitations in realizing excellent low gloss characteristics. In addition, when an excess of the large-diameter conjugated diene rubber polymer is added, physical properties, such as impact strength and weather resistance, may be deteriorated.
In addition, a method of adding a matte filler having a particle size of 5 μm or more to a resin has been proposed, but it has been difficult to realize excellent low gloss characteristics by such a method. In this case, when miscibility between the resin and the matte filler is insufficient, inherent physical properties of a resin, such as impact strength, may be significantly lowered.
As another example, there has been proposed a method of graft-polymerizing a copolymer such as an ethylene-unsaturated carboxylic acid copolymer as a modifier to an ABS polymer prepared by performing emulsion polymerization. Resins prepared using this method have excellent low gloss characteristics and good physical properties such as impact strength. Accordingly, the above method is most widely used to realize low gloss characteristics of a resin. However, the method is difficult to apply when a particular process is not ready, and even when the process is ready, there is a problem that process dependency is large, resulting in a cost problem.